that looks like beach/rock damage. up and down on the beach when the waves come in. To deep to sand out, I would bring to a local shop and have them look at it

Beach/rock damage seems logical. I had one similar deep gouge on the side of my 230VRS where another boat was rafted up to me and his tower rubbed my gel...bad. I never thought it could be repaired by wet sanding but my friend's shop fixed it by sanding. Not sure how long it took, but it came out like new.

that looks like beach/rock damage. up and down on the beach when the waves come in. To deep to sand out, I would bring to a local shop and have them look at it

The previous owner said it's from sanding and I believe it because the whole bottom, below the water line, is like that. It's not obvious from the photos but you can see the swirls especially at the bow.

I can tell you from just having to do a small portion of mine, this is not an easy task. For me the really eye opening thing was the hull was less then a quarter of an inch thick. So in my opinion you will have to re gel. here are a couple of picture of mine i just finished. The hardest parts were getting if off the trailer and sanding over my head for hours.